Photovoltaic devices, capable of converting sunlight and other forms of light energy to electric energy, are increasingly expected as a next-generation energy source in view of global environmental problems. Some known photovoltaic devices have a heterojunction back-contact structure in which electrodes, a p-type semiconductor layer, and an n-type semiconductor layer are formed on a back face of a semiconductor substrate opposite a light-incident face thereof to improve efficiency of conversion of light energy to electric energy (see, for example, Patent Literature 1). Patent Literature 1 discloses a method of manufacturing a photovoltaic device that involves a step of patterning a p-type semiconductor layer and an n-type semiconductor layer on a back face of a substrate by using an etching paste.